(Reuters) -The leaders of No Labels, a group preparing a potential third-party presidential bid, have asked the U.S. Justice Department to investigate a range of Democratic-leaning groups and activists who they say are working to thwart those efforts. The group on Thursday said a public and private pressure campaign by Democrats and allies of President Joe Biden goes beyond legally protected political speech. "There is a group of activists, operatives and party officials who are participating in an alleged illegal conspiracy to use intimidation, harassment and fear against representativ...